Healthy Living

Low and slow diet strategy may help 'Biggest Loser' metabolism

For those wanting to lose weight, exercise can build muscle and burn calories, but it won't alter your resting metabolism by more than 50 to 60 calories a day. (Jeremy Papasso / Boulder Daily Camera)

Dieters who picked up the New York Times recently could hardly be blamed if shock over a study of "Biggest Loser" contestants caused them to spit out their green juice.

The May 2 story, which reported on a study to be published the same day in the journal Obesity, detailed researchers' follow up analysis of contestants who had lost large amounts of weight on the NBC reality show. In short, the study showed that many had regained a good portion of their weight. Four weighed more than they had at the beginning of the show. Not surprising, since various studies have shown that large percentages (amounts vary) of dieters fail to maintain weight loss. What shocked researchers was that participants' resting metabolism rates have slowed, as well, and by unexpectedly large percentages.

Doctors expected metabolisms to be slower after contestants had lost weight, but even after gaining weight back, their resting metabolism rate remained much lower. One contestant, Danny Cahill, has gained back 100 pounds, but still burns 800 calories less than the average man his size. Another contestant, Erinn Egbert, lost about 20 more pounds after the show was over and has kept it off, the only contestant to do so. But that has been a big struggle: Her resting metabolism is 562 calories lower than would be expected for a woman her size.

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Bonnie Jortberg, an assistant professor in the Department of Family Medicine at the University of Colorado School of Medicine, said she was shocked by the results. She had seen research showing that people who had lost significant amounts of weight — more than 50 pounds — experienced a drop in their resting metabolic rate of 200 to 300 calories. However, she says: "When you see a 500- to 600-calorie shift, that's very significant. I can't even get my head around it."

She adds that what research has shown about people who do maintain a lower weight is that they do so by being more active and eating somewhat less. Something less hard to do if the caloric deficit is lower.

Jortberg, who teaches nutrition to medical students at CU, says the human body evolved for a feast/famine environment, slowing metabolism to compensate for periods when food was not plentiful. Modern humans, however, live in a feast/feast world, where food is always available.

If a person weighs 400 pounds, the body should think, "I have enough fat storage for two years," she says, but that's now how it works.

One red flag for Jortberg is that how quickly contestants dropped pounds, losing 3 to 5 percent of their body weight each week.

"We recommend people lose that over three months," she says. "It speaks to the fact that when you have very rapid weight loss, your body just freaks out."

For those who think building muscle can raise their metabolism, Jortberg says: not so much, although exercise is beneficial for many reasons.

"You can change your body composition, so you can build more muscle," she says. "Muscle is more metabolically active. With building more muscle mass, you're maybe increasing your metabolism by 50 or 60 calories a day."

Another finding of the "Biggest Loser" study was that the contestants' levels of leptin, a hormone that controls hunger, had fallen to almost nothing by the end of the show. When studied, their levels of leptin had rebounded to only half of what they were before. That means that strategies such as mindful eating — listening to your body so you eat only when you are hungry — are less effective. They were hungry almost constantly.

One thing that the "Biggest Loser" study does is to serve as a warning to prevent obesity in the first place. Jortberg says one thing people can do is to keep themselves from gaining weight is self-monitoring — weighing frequently and monitoring their activity.

She says she is interested by diets that urge modified fasting — eating only 500 to 600 calories — two days a week as a way to lose weight. She has seen a couple of small studies.

"I think it is intriguing. I'm not sure I'm convinced just yet if that is a way to trick the body, not letting the body get into a prolonged deficit," she says.

Esther Cohen, a registered dietitian with a Boulder practice called The Alchemy of Nourishment, says she wasn't too surprised by the metabolic changes in the "Biggest Loser" contestants, given the extreme diet and exercise regiment they underwent.

"What happens when you lose weight so dramatically is that your body goes into starvation state. Once you significantly cut back your calories, your body is designed to preserve itself," she says. "What you truly want is for your body to go into ketosis, burning fat instead of carbs. Never in human history have we had this abundance of carbohydrate energy, especially carbohydrate energy that is accented with all sorts of neurotoxins, food coloring, flavorings, additives, stimulants affecting the whole hormonal balance."

Cohen is a proponent of eating clean, nutritionally dense food and of cleanses — one or two days of fasting that is supported by broths and juices, as a way to help the body reset the system. She says she has had clients who have lost more than 50 pounds and have kept it off. She doesn't track them, but many clients have kept in touch, coming to her for spring and fall cleanses to keep themselves from falling back into poor habits.

Cohen says that in addition to the abundance of poor quality — and tempting — food, stress plays a role in whether we truly nourish ourselves or eat to damp down anxiety.

"The truth is we're so out of a real, nourishing relationship to food," she says.

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